Fabrication of Ta-Al-N Thin Films and Its Cu Diffusion on Barrier Properties

Ta-Al-N thin films on Si wafer were prepared by RF reactive magnetron sputtering in a N-2/Ar ambient. Then the stacked structures of Cu/Ta-Al-N/Si were prepared and annealed at temperatures varied from 400 degrees C to 900 degrees C for 5 minutes in a N-2 ambient tube. Four-point probe (FPP) sheet resistance measurement, Atomic force microscope (AFM), Scanning electron microscope(SEM), Alpha-Step IQ Profilers and X-ray Diffraction(XRD) were used to investigate the composition, morphology and the diffusion barrier properties of the thin films. The results show that with the increasing of Al component, the surface of Ta-Al-N thin-films became finer, the sheet resistance became higher, and after annealing at 800 degrees C/300S FA, Cu diffusion through Ta-Al-N barrier didn't not occurred. Results show that Ta-Al-N thin-films could act as diffusion barrier for new generation integrated circuits due to its excellent high temperature properties.